Problem: address parsing code is tied to the TCP code

Solution: Factor the code into a different file with a well defined API and add
unit tests.

CMakeLists.txt

@@ -603,6 +603,7 @@ set (cxx-sources
         udp_address.cpp
         scatter.cpp
         gather.cpp
+	ip_resolver.cpp
 		zap_client.cpp
 		# at least for VS, the header files must also be listed
 		address.hpp

Makefile.am

@@ -83,6 +83,8 @@ src_libzmq_la_SOURCES = \
 	src/io_thread.hpp \
 	src/ip.cpp \
 	src/ip.hpp \
+	src/ip_resolver.cpp \
+	src/ip_resolver.hpp \
 	src/ipc_address.cpp \
 	src/ipc_address.hpp \
 	src/ipc_connecter.cpp \
@@ -895,7 +897,8 @@ if ENABLE_STATIC
 test_apps += \
 	unittests/unittest_poller \
 	unittests/unittest_ypipe \
-	unittests/unittest_mtrie
+	unittests/unittest_mtrie \
+	unittests/unittest_ip_resolver
 
 unittests_unittest_poller_SOURCES = unittests/unittest_poller.cpp
 unittests_unittest_poller_CPPFLAGS = -I$(top_srcdir)/src ${UNITY_CPPFLAGS} $(CODE_COVERAGE_CPPFLAGS)
@@ -920,6 +923,14 @@ unittests_unittest_mtrie_LDADD = $(top_builddir)/src/.libs/libzmq.a \
 	${src_libzmq_la_LIBADD} \
 	${UNITY_LIBS} \
 	$(CODE_COVERAGE_LDFLAGS)
+
+unittests_unittest_ip_resolver_SOURCES = unittests/unittest_ip_resolver.cpp
+unittests_unittest_ip_resolver_CPPFLAGS = -I$(top_srcdir)/src ${UNITY_CPPFLAGS} $(CODE_COVERAGE_CPPFLAGS)
+unittests_unittest_ip_resolver_CXXFLAGS = $(CODE_COVERAGE_CXXFLAGS)
+unittests_unittest_ip_resolver_LDADD = $(top_builddir)/src/.libs/libzmq.a \
+	${src_libzmq_la_LIBADD} \
+	${UNITY_LIBS} \
+	$(CODE_COVERAGE_LDFLAGS)
 endif
 
 check_PROGRAMS = ${test_apps}